Fail download-data gracefully if no pairs-file exists

freqtrade/utils.py

@@ -5,6 +5,7 @@ from typing import Any, Dict, List
 
 import arrow
 
+from freqtrade import OperationalException
 from freqtrade.configuration import Configuration, TimeRange
 from freqtrade.configuration.directory_operations import create_userdata_dir
 from freqtrade.data.history import refresh_backtest_ohlcv_data
@@ -70,6 +71,11 @@ def start_download_data(args: Dict[str, Any]) -> None:
         time_since = arrow.utcnow().shift(days=-config['days']).strftime("%Y%m%d")
         timerange = TimeRange.parse_timerange(f'{time_since}-')
 
+    if 'pairs' not in config:
+        raise OperationalException(
+            "Downloading data requires a list of pairs."
+            "Please check the documentation on how to configure this.")
+
     dl_path = Path(config['datadir'])
     logger.info(f'About to download pairs: {config["pairs"]}, '
                 f'intervals: {config["timeframes"]} to {dl_path}')

tests/test_utils.py

@@ -1,4 +1,5 @@
 import re
+from pathlib import Path
 from unittest.mock import MagicMock, PropertyMock
 
 import pytest
@@ -7,7 +8,7 @@ from freqtrade import OperationalException
 from freqtrade.state import RunMode
 from freqtrade.utils import (setup_utils_configuration, start_create_userdir,
                              start_download_data, start_list_exchanges)
-from tests.conftest import get_args, log_has, log_has_re, patch_exchange
+from tests.conftest import get_args, log_has, patch_exchange
 
 
 def test_setup_utils_configuration():
@@ -114,8 +115,27 @@ def test_download_data_no_exchange(mocker, caplog):
         'freqtrade.exchange.Exchange.markets', PropertyMock(return_value={})
     )
     args = [
-        "download-data"
+        "download-data",
         ]
     with pytest.raises(OperationalException,
                        match=r"This command requires a configured exchange.*"):
         start_download_data(get_args(args))
+
+
+def test_download_data_no_pairs(mocker, caplog):
+    mocker.patch.object(Path, "exists", MagicMock(return_value=False))
+
+    mocker.patch('freqtrade.utils.refresh_backtest_ohlcv_data',
+                 MagicMock(return_value=["ETH/BTC", "XRP/BTC"]))
+    patch_exchange(mocker)
+    mocker.patch(
+        'freqtrade.exchange.Exchange.markets', PropertyMock(return_value={})
+    )
+    args = [
+        "download-data",
+        "--exchange",
+        "binance",
+    ]
+    with pytest.raises(OperationalException,
+                       match=r"Downloading data requires a list of pairs\..*"):
+        start_download_data(get_args(args))